OPTIMIZATION AND PERFORMANCE OF HIGH-RESOLUTION THERMOMETERS IN LOW-EARTH-ORBIT

We describe the development of paramagnetic salt thermometers, using a SQUID magnetometer readout, which achieve resolutions approaching 10( -11) K/square-root Hz and drift on the order of 10(-14) K/sec. Optimiz ation of the pickup coil and improved thermal contact to the salt mate rial improve the performance markedly over previous designs. The curre nt design was successfully flown in low earth orbit. The effects of pr imary cosmic rays degraded the effective noise performance by a factor of 2 to 4. We discuss ways to mitigate the effects of the cosmic rays .